I asked a pretty knowledgable guy at my LBHS and he suggests the following:
DME and LME can be stored at room temperature (if a very long time, the fridge)
Dry Yeast at room temperature and liquid yeast in the fridge
Cracked grains and hops in the freezer.
I checked with a customer service person at one of the online homebrew supply stores and they said the same thing.
You might get some different answers, but I think this is a good guide and I have stored a kit for over two months this way with no ill effects.
Good luck!!